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SND_2015_I1389908

Cross section for $e^+e^-\to \pi^+\pi^-\pi^0$ between 1.05 and 2 GeV.
Experiment: SND (VEPP-2M)
Inspire ID: 1389908
Status: VALIDATED
Authors:
  • Peter Richardson
References:
  • J.Exp.Theor.Phys. 121 (2015) no.1, 27-34
Beams: e+ e-
Beam energies: ANY
Run details:
  • e+ e- to hadrons

Measurement of the cross section for $e^+e^-\to \pi^+\pi^-\pi^0$ by SND for energies between 1.05 and 2 GeV.

Source code: SND_2015_I1389908.cc
 1// -*- C++ -*-
 2#include "Rivet/Analysis.hh"
 3#include "Rivet/Projections/FinalState.hh"
 4
 5namespace Rivet {
 6
 7
 8  /// @brief Add a short analysis description here
 9  class SND_2015_I1389908 : public Analysis {
10  public:
11
12    /// Constructor
13    RIVET_DEFAULT_ANALYSIS_CTOR(SND_2015_I1389908);
14
15
16    /// @name Analysis methods
17    //@{
18
19    /// Book histograms and initialise projections before the run
20    void init() {
21      // Initialise and register projections
22      declare(FinalState(), "FS");
23      book(_num3pi, "TMP/num3");
24    }
25
26
27    /// Perform the per-event analysis
28    void analyze(const Event& event) {
29      const FinalState& fs = apply<FinalState>(event, "FS");
30
31      map<long,int> nCount;
32      int ntotal(0);
33      for (const Particle& p : fs.particles()) {
34	nCount[p.pid()] += 1;
35	++ntotal;
36      }
37      if(ntotal!=3) vetoEvent;
38      if(nCount[-211]==1&&nCount[211]==1&&nCount[111]==1)
39	_num3pi->fill();
40    }
41
42
43    /// Normalise histograms etc., after the run
44    void finalize() {
45      double sigma = _num3pi->val();
46      double error = _num3pi->err();
47      sigma *= crossSection()/ sumOfWeights() /nanobarn;
48      error *= crossSection()/ sumOfWeights() /nanobarn; 
49      Scatter2D temphisto(refData(1, 1, 1));
50      Scatter2DPtr mult;
51      book(mult, 1, 1, 1);
52      for (size_t b = 0; b < temphisto.numPoints(); b++) {
53	const double x  = temphisto.point(b).x();
54	pair<double,double> ex = temphisto.point(b).xErrs();
55	pair<double,double> ex2 = ex;
56	if(ex2.first ==0.) ex2. first=0.0001;
57	if(ex2.second==0.) ex2.second=0.0001;
58	if (inRange(sqrtS()/GeV, x-ex2.first, x+ex2.second)) {
59	  mult->addPoint(x, sigma, ex, make_pair(error,error));
60	}
61	else {
62	  mult->addPoint(x, 0., ex, make_pair(0.,.0));
63	}
64      }
65    }
66
67    //@}
68
69
70    /// @name Histograms
71    //@{
72    CounterPtr _num3pi;
73    //@}
74
75
76  };
77
78
79  // The hook for the plugin system
80  RIVET_DECLARE_PLUGIN(SND_2015_I1389908);
81
82
83}